Environmentally isolated waveguide display

Abstract

A waveguide display having an input image generator providing image light projected over a field of view; a waveguide having first and second external surfaces; and at least one grating optically coupled to the waveguide for extracting light towards a viewer. The waveguide has a lateral refractive index variation between said external surfaces that prevents any ray propagated within the waveguide from optically interacting with at least one of the external surfaces.

What is claimed is: 
     
       1. A waveguide display, comprising:
 an input image generator providing image light projected over a field of view; 
 a waveguide having first and second external surfaces; and 
 at least one grating optically coupled to said waveguide for extracting light from said waveguide towards a viewer of said display, 
 wherein said waveguide has a lateral refractive index variation between said external surfaces that prevents rays propagating within said waveguide from optically interacting with at least one of said external surfaces and wherein said waveguide contains a GRIN medium, wherein said grating is disposed within said GRIN medium. 
 
     
     
       2. The apparatus of  claim 1  wherein said waveguide contains a GRIN medium wherein said grating is disposed in proximity to one of said external surfaces. 
     
     
       3. The apparatus of  claim 1  wherein said waveguide comprises a first waveguide portion containing a GRIN medium abutting a second waveguide portion operating in TIR and containing at least one additional grating for extracting light from said second waveguide portion towards a viewer of said display. 
     
     
       4. The apparatus of  claim 1  wherein said waveguide further comprises an input grating. 
     
     
       5. The apparatus of  claim 1  immersed in air. 
     
     
       6. The apparatus of  claim 1  providing one of a HUD, HMD or a light field display. 
     
     
       7. The apparatus of  claim 1  wherein said waveguide is curved. 
     
     
       8. The apparatus of  claim 1  wherein said waveguide is optically coupled to at least one TIR waveguide portion, each said TIR waveguide portion containing at least one grating. 
     
     
       9. The apparatus of  claim 1  wherein said waveguide comprises a stack of GRIN waveguides optically coupled to a stack of TIR waveguides, each said TIR waveguide containing at least one grating. 
     
     
       10. The apparatus of  claim 1  wherein said waveguide is immersed in a low refractive index external medium and comprises a high refractive index core sandwiched by a low refractive index clad layer and at least one grating layer, wherein TIR takes place between the interface of said core layer and said grating layer and the interface of said grating layer and said external medium. 
     
     
       11. The apparatus of  claim 10  wherein said core and said grating layer have substantially same average refractive index. 
     
     
       12. The apparatus of  claim 10  wherein said core has a refractive index greater than said grating layer average index. 
     
     
       13. The apparatus of  claim 10  further comprising low refractive index layers overlaying at least one of said grating layer and said low refractive index clad layer. 
     
     
       14. The apparatus of  claim 10  wherein said grating layer comprises a grating sandwiched by transparent substrates, said grating layer and said substrates having similar refractive indices. 
     
     
       15. The apparatus of  claims 1  wherein said grating layer comprises an input grating and an extraction grating. 
     
     
       16. The apparatus of  claim 1  further comprising a beamsplitter layer. 
     
     
       17. The apparatus of  claim 1  wherein said image light is collimated. 
     
     
       18. The apparatus of  claim 1  wherein said grating is one of a Bragg Grating, a surface relief grating or a switchable Bragg grating recorded in a HPDLC material, a uniform modulation HPDLC material or a reverse mode HPDLC material.